W.C. Russell 5 mi. N Cerr0 Campana, 5600 ft., Chih, Mex. July 4 1959 with a light. The saccus chater will some- times be stimulated by the tulle of the ordinary Bufo. The latter also popped out all over the place as well as the spadefoot immediately after rains starts. One wonders how deep the Bulos are to withstand the hot dry season & still be able to emerge so soon with the coming of rain. I have spent 4 nights running a line of mouse traps in the wash and on the desert plane at mouth of canyon. This so called desert has quite a heavy growth of grass in patches - not uniformly distributed. It has not been seriously overgrazed. It is in these dense patches of grass where we find many old & some new Sigmodon runs. In burr construction and diurnal+ nocturnal activities this animal closely resembles the microtines. Due to activities of insects? At least 1/3 of traps are sprung. The mouse population is made up of a variety of species but not too many individuals of a given species per acre. A line of 50 traps will produce the following species; Dipodomys ordii + merriami, Perognathus flavus, hispidulus & a penniculates, Onychomys torridus, 2 Reithrodontomyx, Sigmodon, Peromyscus maniculatus & Notoma Lepida.